The compile-time functions that operate on ratio<N,D> require the
cumbersome and error-prone "evaluation" of a type member using a
meta-programming style that predates the invention of template aliases.
Thus, multiplying three ratios a, b, and c requires the expression:

ratio_multiply<a, ratio_multiply<b, c>::type>::type

The simpler expression:

ratio_multiply<a, ratio_multiply<b, c>>

Could be used by if template aliases were employed in the definitions.

[
Post Summit:
]

Jens: not a complete proposed resolution: "would need to make similar change"

Consensus: We agree with the direction of the issue.

Recommend Open.

[
2009-05-11 Daniel adds:
]

Personally I'm not in favor for the addition of:

typedef ratio type;

For a reader of the standard it's usage or purpose is unclear. I haven't
seen similar examples of attempts to satisfy non-feature complete compilers.

[
2009-05-11 Pablo adds:
]

The addition of type to the ratio template allows the previous style
(i.e., in the prototype implementations) to remain valid and permits the
use of transitional library implementations for C++03 compilers. I do
not feel strongly about its inclusion, however, and leave it up to the
reviewers to decide.

[
Batavia (2009-05):
]

Bill asks for additional discussion in the issue
that spells out more details of the implementation.
Howard points us to issue 948
which has at least most of the requested details.
Tom is strongly in favor of overflow-checking at compile time.
Pete points out that there is no change of functionality implied.
We agree with the proposed resolution,
but recommend moving the issue to Review
to allow time to improve the discussion if needed.